Detect if node is half-dead with an iRule?

pool foo accepts 3-ways handshake but not responding any http request. i tried to re-select pool foo2 instead but i got - Address in use tcl error message (and of course, bigip sent reset to both sides).

[root@ve1023:Active] config  b virtual bar list
virtual bar {
   snat automap
   pool foo
   destination 172.28.19.79:80
   ip protocol 6
   rules myrule
   profiles {
      http {}
      tcp {}
   }
}
[root@ve1023:Active] config  b pool foo list
pool foo {
   members 200.200.200.101:88 {}
}
[root@ve1023:Active] config  b pool foo2 list
pool foo2 {
   members 200.200.200.101:80 {}
}
[root@ve1023:Active] config  b rule myrule list
rule myrule {
   when RULE_INIT {
        set static::response_timeout  5
}

when HTTP_REQUEST {
        log local0. "Received request, beginning response monitor interval. [clock seconds]"
}

when LB_SELECTED {
        set monitor_id [\
                after $static::response_timeout {
                        LB::reselect pool foo2
                        log local0. "Timeout $static::response_timeout milliseconds elapsed without server response. [clock seconds]"
                }\
        ]
}

when HTTP_RESPONSE {
        log local0. "Received server response."
        if {[info exists monitor_id]} {
                log local0. "Canceling after script with id $monitor_id"
                after cancel $monitor_id
        }
}
}


 curl -i http://172.28.19.79
curl: (52) Empty reply from server


Nov 18 00:16:02 local/tmm info tmm[4766]: Rule myrule : Received request, beginning response monitor interval. 1321604162
Nov 18 00:16:02 local/tmm err tmm[4766]: 01220001:3: TCL error: myrule  - Address in use (line 1)     invoked from within "LB::reselect pool foo2"


00:16:02.240879 IP 172.28.19.253.34199 > 172.28.19.79.80: S 3035055119:3035055119(0) win 5840 
00:16:02.240917 IP 172.28.19.79.80 > 172.28.19.253.34199: S 2804861295:2804861295(0) ack 3035055120 win 4380 
00:16:02.244080 IP 172.28.19.253.34199 > 172.28.19.79.80: . ack 1 win 46 
00:16:02.244104 IP 172.28.19.253.34199 > 172.28.19.79.80: P 1:155(154) ack 1 win 46 
00:16:02.244203 IP 200.200.200.10.34199 > 200.200.200.101.88: S 3752179749:3752179749(0) win 4380 
00:16:02.244864 IP 200.200.200.101.88 > 200.200.200.10.34199: S 195117275:195117275(0) ack 3752179750 win 5792 
00:16:02.244875 IP 200.200.200.10.34199 > 200.200.200.101.88: . ack 1 win 4380 
00:16:02.244886 IP 200.200.200.10.34199 > 200.200.200.101.88: P 1:155(154) ack 1 win 4380 
00:16:02.245899 IP 200.200.200.101.88 > 200.200.200.10.34199: . ack 155 win 54 
00:16:02.249309 IP 200.200.200.10.34199 > 200.200.200.101.88: R 155:155(0) ack 1 win 4380
00:16:02.249333 IP 172.28.19.79.80 > 172.28.19.253.34199: R 1:1(0) ack 155 win 4534